The present disclosure relates to a toner for developing an electrostatic latent image and in particular relates to a positively chargeable toner for developing an electrostatic latent image that includes toner particles including an external additive.
Electrophotography is an example of a technique that uses an electrostatic latent image developing toner in order to form an image. Electrophotography involves irradiating a charged photosensitive drum with light, thereby forming an electrostatic latent image on the surface of the photosensitive drum. The electrostatic latent image is subsequently developed using toner to form a toner image. The toner image that is formed is transferred onto a recording medium. Through the above process, an image is formed on the recording medium.
Electrostatic latent image developing toners are commonly known in which an external additive is caused to adhere to the surface of toner mother particles in order to impart fluidity on the toner, optimize charge of the toner, or improve properties of the toner that facilitate cleaning thereof. The toner mother particles contain a binder resin and internal additives (for example, one or more out of a colorant, a charge control agent, a releasing agent, and a magnetic material). The external additive is commonly made from an inorganic material (for example, silica or titanium oxide).
However, fine particles of an inorganic material, such as silica particles or titanium oxide particles, tend to become negatively charged. In consideration of the above, in a situation in which fine particles of an inorganic material such as described above are to be included in a positively chargeable toner, it has been proposed that positively chargeable polar groups be introduced onto the surface of the inorganic particles. For example, a toner has been proposed in which the external additive has been subjected to surface treatment with an amino group-containing compound. In another example, a toner has been proposed that includes fine particles containing titanium oxide that has been subjected to surface treatment with an alkyl trialkoxysilane and silica that has been subjected to treatment with an ammonium-modified polysiloxane.